Electrohydraulic transducers

ABSTRACT

This disclosure relates to electrohydraulic transducers of the type where electrical energy is discharged across a gap between a pair of electrodes to create a shock wave which expands a flexible chamber to urge a tubular workpiece telescopically externally thereof into conformity with a mold cavity, and includes an internal cage structure for supporting the chamber and at least one of the electrodes, and means for clamping the tubular workpiece at a predetermined position relative to the cavity prior to a forming operation.

United States Patent [72] inventors Donald J. Roth Chicago Heights; Carl A. Pesce, Chicago. both of, 111. [21] Appl. Nov 762,523 [22] Filed Sept. 25, 1968 [4S] Patented July 20, 1971 [73] Assignee Continental Can Company, lnc.

New York, N.Y.

[54} ELECTROHYDRAULIC TRANSDUCERS 7 Claims, 7 Drawing Figs.

[52] U.S.Cl 72/56, 72/63 [51] lnt.Cl... 4 821d 26/12 [50] Field ofSearch. 72/56, 63; 29/421 E; 340/12 R [56] References Cited UNITED STATES PATENTS 2,559,227 7/1951 Rieber 72/56 X 3,222,902 12/1965 Brejeha etal.... 72/56 3,225,578 12/1965 Krieger i i i 72/56 lnoue,

lllgeni. M Herring, Jr Maier lnoue Wesley Smith..,..

Erlandson Primary Examiner- Richard J. Herbst Attorney-Diner, Brown, Ramik & Holt relative to the cavity prior to a forming operation.

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ELECTROHYDRAULIC TRANSDUCERS l A primary object of this invention is to provide a novel electhe electrode-electrode gap whereupon the resultant electrohydraulic effect produces a momentary shock wave which expands the chamber radially outwardly and forces a tubular workpiece in a similar direction into conformity with a mold cavity.

A further object of this invention is to provide a novel transducer of the type heretofore described wherein means are provided for clamping a bottom wall of the tubular element between the chamber means and an exterior supporting element, as well as for clamping an opposite peripheral edge portion of the tubular element to achieve reformed tubular elements of uniform axial length.

A further object of this invention is to provide a novel electrohydraulic transducer of the type heretofore described wherein means are provided for increasing the clamping forces of the peripheral edge portion clamping means in proportion to an increase in pressure internally of the chamber.

Still another object of this invention is to provide a novel electrohydraulic transducer as heretofore set forth wherein the electrodes are positioned in either axially opposed or spaced-para lel relationship, and in each case means are provided for adjusting the electrode-electrode gap therebetween to compensate for erosion caused by electrical discharge.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims subject matter, and the several views illustrated in the accompanying drawings.

In the drawings:

FIG. I is a fragmentary axial sectional view taken through an electrohydraulic transducer of this invention, and illustrates a rigid cage surrounded by a flexible baglike element defining a chamber, and a pair of parallel electrodes positioned within the chamber.

FIG. 2 is a cross-sectional view taken generally along line 2-2 of FIG. 1, and illustrates a manner in which a pair of split molds are closed about the transducer prior to the operation thereof.

FIG. 3 is a fragmentary sectional view of another electrohydraulic transducer constructed in accordance with this invention, and illustrates another cage which supports a pair of axially opposed electrodes interiorly of a fluid medium chamber.

FIG. 4 is a fragmentary sectional view taken generally along line 4-4 of FIG. 3, and illustrates a split mold positioned in external telescopic relationship to the transducer prior to the operation thereof.

FIG. 5 is a longitudinal sectional view taken through another transducer of this invention, and illustrates another cage and chamber construction, as well as means for clamping a free peripheral edge portion of a tubular workpiece relative to a split mold and means for increasing the clamping force in proportion to an increase in the pressure of a fluid medium introduced into the chamber.

FIG. 6 is a top plan view of the transducer of FIG. 5, and illustrates electrical connections and hydraulic passages thereof.

FIG. 7 is a cross-sectional view taken generally along line 7-7 of FIG. 5, and illustrates the closed position of a split mold relative to the transducer prior to the operation of the latter.

Referring first to FIGS. 1 and 2 of the drawings a novel electrohydraulic transducer constructed in accordance with this invention is generally designated by the reference numeral 10 and includes a internal cage structure 11 defined by a pair of circular-spaced platelike members 12, 13. The plate 12 is secured to one of four supporting rods 14 through 17 by identical bolts 19. Opposite end portions 18 of each of the rods 14 through 17 are reduced and threadably secured to a rigid tubular support 20 after being telescopically directed through bores 21 of the member I3.

Prior to securing the rods 14 through 17 in the position shown in FIG. 1 a radially inwardly directed flange 22 of a flexible tubular sleeve 23 is positioned as shown in FIG. I whereupon the tightening of the rods 14 through 17 clamps the flange 22 between the rigid support 20 and the member 13. The opposite end of the flexible tube 23 is likewise provided with a radially inwardly directed flange 24 which is clamped in position between the member 22 and a plate 25 by one or more screws 26. The members lZ, 13 and the flexible element 23 thereby define a chamber 27 into which a fluid medium, such as a low (4 percent) concentrate salt solution, may be introduced through a port 28 and removed through a port 30. The port 28 is coupled by a conduit 31 to a pump 32 for not only filling the chamber 27 but pressurizing the fluid medium to between 600-800 p.s.i. incident to the performance of a reforming operation under the influence of an electrical energy discharge, which will be described more fully hereinafter.

A pair of electrodes 33,34 are positioned internally of the chamber 27 in generally spaced-parallel relationship and terminate at cylindrical end portions 35, 36' between which is established an electrode-electrode gap 37. Threaded portions (unnumbered) of the electrodes 33, 34 permit the electrodes to be rotated to position the opposed peripheral surfaces of the end portions 35, 36 in predetermined spaced relationship to each other. The rotatable mounting of electrodes 33, 34 thereby permit the gap 37 to be adjusted simply be rotating either or both electrodes which additionally compensates for the erosion of the end portions 35, 36 during to continuous electrical discharges thereacross. The rotation of the electrodes 33, 34 also permits the axial position of the end portions 35, 36 to be adjusted relative to the chamber 27, and the parallel disposition of the electrodes also presents a low inductance path for the discharge of electrical energy which in turn allows a more efficient transfer of the energy from electrical to mechanical. The threaded end portions of electrodes 33, 34 are received in internally threaded insulators 38, 39 respectively.

The transducer 10 is operated by first placing a tubular element T into external telescopic relationship to the chamber 27 and closing thereabout a pair of mold bodies 40, 41 as best shown in FIG. 2. The mold bodies 40, 41 preferably include vent openings 43 which open into a cavity 44 defined by the mold bodies 40,41.

When thus positioned the pump 42 is energized by a suitable motor (not shown) to conduct the fluid medium (not shown) into the chamber 27 through the conduit 31 and the port 28. At this time a valve (not shown) in a conduit (also not shown) connected to the port 30 is closed. As the pressure of the fluid medium in the chamber 27 increases the flexible tubular element 23 expands radially outwardly and contours the tubular element T to the general configuration of the cavity I, 44. After a predetermined pressure has been reached (600- 800 p.s.i.) a suitable switch is closed to discharge electrical energy stored in a capacitor or an inductor through the electrodes 33, 34 and across the gap 37. This discharge creates a rapidly extending plasma bubble at the gap 37 and the interaction of the bubble and the incompressible fluid medium causes a mechanical shock wave to be formed which moves radially outwardly through the fluid medium and the flexible element 23 to expand the tubular element T into intimate conformity with the cavity 44.

Reference is now made to FIGS. 3 and 4 of the drawings which illustrate another electrohydraulic transducer 50 which includes an internally generally rigid cage 49 defined by a pair of spaced platelike members 51, 52'which include respectively axial bores 53, 54 and a plurality of identical circumferential bores 55, 56 which are respectively counterbored at 57, 58.

A plurality of identical supporting rods 60 through 63 having enlarged flange portions 64, 65 are positioned relative to the bores 55, 56, and the counterbores 57, 58 in the manner clearly illustrated in F IG. 3. The left-handmost end portions of the rods 60 through 63 pass through bores 66 of a rigid supporting member 67, and are secured in position by identical nuts 68. The opposite end portions of the rods 60 through 63 are also threaded and are secured in position by a plurality of identical nuts 70. Suitable annular sealing means 71 through 73 are provided for preventing the escape of a fluid medium (not shown) from a chamber 74 into which it is introduced and removed by ports 75, 76 in the member 51 and corresponding bores in the support member 57 which are coupled by conduits (not shown) to suitable pumps.

The chamber 74 is peripherally closed by a flexible member 77 which is secured in exterior encircling relationship to the chamber 74 by a pair of exterior clamping bands 78, 80.

An electrode 81 is positioned in the bore 54 and projects into the chamber 74 in coaxial relationship to an electrode 82 projecting outwardly of the bore 53. A pair of O-ring seals 83, 84 and a washer 85 prevent fluid medium in the chamber 74 from escaping outwardly thereof between the electrodes 81, 82 and the bores 54, 53, respectively.

The electrodes 81, 82 are mounted for axial adjustment relative to each other to adjust the size of the electrode-electrode gap (unnumbered). The adjusting means is defined by a pair of threaded portions 86, 87 of the electrode 82 upon which are received nuts 88, 90 respectively. A reduced end portion 91 of electrode 82 is slidably received in a bore 92 of a cap 93 welded or otherwise secured to a tubular member 94 of the stationary support member 67.

In order to adjust the electrode-electrode gap the member 94 is slid to the left and outwardly of a tubular insulator 95 after which the nut 88 and the nut 90 are appropriately rotated to increase or decrease the length of the electrode projecting beyond the right-handmost face of the cap 93. Thereafter the tube 94 is reinserted into the tubular insulator 95 and the electrode is repositioned as shown with the only change being that of the electrode-electrode gap. 1

The transducer50 is operated in conjunction with a pair of mold bodies 96, 97 ofa split mold which define a tubular cavity 98 to which is conformed a tubular workpiece or element T upon the operation of the transducer50 in the manner heretofore described relative to the transducer 10.

Reference is now made to FIGS. through 7 of the drawings which illustrate another electrohydraulic transducer 100 which includes an upper stationary electrically conductive supporting plate 101 to which is connected a conductor 102. The plate 101 forms a support for a cage 103 defined by a pair of annular insulating members 104, 105 spaced from a member 106 by a plurality of electrically conductive rods 107 which at opposite ends thereof are welded to the plate 101 and to the member 106. Electrode 108 is positioned within the tubular member 104 and is positioned in coaxial relationship to. an electrode 110 which is connected to the member 106 by a tapered annular clamping plug 111 and a nut 112 threadably secured to an internally threaded recess 113.

The annular member 105 is received in a housing 114 which is clamped to the undersurface of the plate 101 by a split ring 115 add a plurality of bolts 116. A seal 117 is positioned between the exterior of the annular member 105 and a bore 1 18 to prevent fluid seepage.

The lower end portion of the housing 114 includes a fluid chamber 120 in which is slidably mounted an annular piston 121 which is illustrated in its lowermost position by means of an annular flange 122 secured to the housing 114 by bolts 123. An upper peripheral portion 124 of a flexible baglike element 125 is clamped to the piston 121 by means of an annular nut 129 which is threadably secured to the piston 121 and is prevented from inadvertent unthreading during the operation of the transducer 100 by means of a pin 126-which projects intoan upwardly opening groove 127 of the nut 129. The function of the piston 121 is a clamp a peripheral edge portion P of a tubular element T such as a can body, between an annular clamping surface 130 of the piston 121 and an opposing clamping surface 131 of a pair of mold bodies 132, 133 defining a cavity 134 therebetween.

A lower open end portion of the cavity 134 is closed by a circular plate 135 which is reciprocated by conventional means (not shown) in the direction of the unnumbered double-headed arrow associated therewith. The plate 135 is shown in its uppermost position at which a bottom wall (unnumbered) of the tubular element T is clamped between the upwardly directed force of the plate 135 which is resisted by the rigidity of the cage 103 and the lowermost surface of the member 106.-

A fluid medium, such as low concentrate saline solution, is introduced into a chamber 140 of the transducer through a passage 141 in the plate 101 and a passage 142 in the annular member 105. A port 143 places the port 142 in fluid communication with the chamber for applying the necessary force to move the piston 121 downwardly to apply clamping pressure between the surfaces 130, 131.

A passage 144 (FIG. 6) in the annular member 105 and a bore 145 permit the chamber 140 to be drained in the manner heretofore described relative to the transducer 10 of FIG. 1.

Assuming that the mold bodies 132, 133 have been moved in the direction of the unnumbered headed arrows associated therewith and that the plate 135 has been moved downwardly,

an operation of the transducer is initiated by first positioning the tubular workpiece or element T upon the upper surface of the plate 135 and moving the same upwardly until the peripheral edge portion T of the workpiece contacts and seats against the clamping surface of the piston 121 which at this time is positioned slightly more upwardly from that shown in FIG. 5 with the bottom surface of the groove in contact with the end face of the pin 126. In this position the bottom wall of the tubular element T is clamped in a predetermined position as established by the clamping action between the cage 103 and the plate 135.

The mold bodies 132, 133 are then closed in a conventional manner during which time the clamping surface 131 is brought into underlying contact with the exterior surface of the peripheral edge portion P. I

The fluid medium is then introduced into the chamber 140 through the passage 14] and the passage 142 which not only causes the chamber 140 to fill, but also the chamber 120. The fluid medium in the chamber is then progressively increased in pressure by conventional means (not shown) during which time the baglike element 125 is progressively expanded radially outwardly and eventually conforms the tubular element T, to the general configuration of the cavity 134. During this progressive increase in the pressure of the fluid medium the clamping force between the surfaces 130, 131 is increased because a like pressure is established in the chamber 120 via the port 143. Thus, irrespective of the pressure within the chamber 140 the peripheral edge portion P is securely clamped at a desired predetermined position. Due to this clamping and the clamping action between the member 106 and the plate the axial height of each finally reformed tubular element is substantially identical and is not foreshortened, as would occur if the peripheral edge portion P were not clamped whereupon the expansion of the tubular element would draw the peripheral edge P axially downwardly thereby resulting in workpieces of indiscriminate heights.

After the fluid medium in the chamber has been increased to a predetermined amount between, for example, 600 to 800 p.s.i., energy stored in a capacitor or an inductor is transferred by the closing of a switch (not shown) to the electrodes 108, 110, it being noted in this regard that each of the components 101, 107, 106, and 112 areconstructed from electrically conductive material. The discharge of the electrical energy between the electrodes 108, 110 creates a bubble in a manner heretofore described which forces the tubular element T, into intimate contact with the cavity 134, thereby completing the reforming operation.

The fluid medium is then purged from the chamber 140 through the passages 144, 145 which creates a partial vacuum sufficient to lift the piston 121 to release the clamping force between the surfaces 130, 131. The baglike element 125 is thereby also collapsed against the supporting rods 107, as shown in phantom outline in FIG. 7, whereby upon the opening of the split molds 132, 133, downward movement of the plate 135 permits the reformed tubular element T to be readily withdrawn downwardly and subsequently discharged.

While preferred forms and arrangement of parts have been shown in illustrating the invention, it is to be clearly understood that various changes in details and arrangement of parts may be made without departing from the spirit and scope of the invention as defined in the appended claimed subject matter.

We claim:

1. An electrohydraulic transducer comprising flexible chamber means about which a tubular element is adapted to be exteriorly telescopically positioned, means for introducing a fluid medium into said chamber means, means for supporting a pair of electrodes in said chamber means whereby upon the discharge of electrical energy across said electrodes the resultant electrohydraulic effect produces a momentary hydraulic shock wave which expands said chamber means and forces said tubular element radially outwardly thereby reforming the initial configuration thereof, clamping surface means interiorly contacting a free peripheral edge portion of the tubular element, clamping surface means exteriorly contacting said free peripheral edge portion, means for relatively moving said clamping surface means toward each other to clamp the free peripheral edge portion of the tubular element therebetween thereby clampingly positioning the tubular element at a predetermined position relative to said chamber means, relatively rigid cage structure means disposed partially interiorly of said chamber means, a fluid cylinder carried by said cage structure means, a piston of said fluid cylinder having a surface portion defining said interior clamping surface means, and means for introducing fluid into said fluid cylinder for moving said piston between clamping and unclamping positions relative to said exterior clamping surface means.

2. The electrohydraulic transducer as defined in claim 1 wherein said piston is of an annular configuration and is in exterior telescopic relationship to said chamber means.

3. The electrohydraulic transducer as defined in claim 2 wherein said chamber means is a flexible baglike element having a closed end, one of said pair of members is supported at said closed end by said supporting means, and one of said electrodes is carried by said one member.

4. An electrohydraulic transducer comprising flexible chamber means about which a tubular element is adapted to be exteriorly telescopically positioned, means for introducing a fluid medium into said chamber means, means other than said flexible chamber means for clamping the tubular element at a predetermined position relative to said chamber means, and means for increasing the force of said clamping means in proportion to an increase in pressure of said fluid means in said chamber means.

5. The electrohydraulic transducer as defined in claim 4 including means for supporting a pair of electrodes in said chamber means whereby upon the discharge of electrical energy across said electrodes the resultant electrohydraulic effect produces a momentary shock wave which expands said chamber means and forces said tubular element radially outwardly thereby reforming the initial configuration thereof.

6. The electrohydraulic transducer as defined in claim 4 wherein said clamping means includes piston means exteriorly of said chamber means, and said force-increasing means is a fluid circuit placing said piston in fluid communication with said chamber means.

7. The electrohydraulic transducer as defined in claim 4 wherein said clamping means includes a piston axially movable in a fluid cylinder, said piston having a surface portion defining a surface for clam ing against a free inner peripheral surface of said tubular e ement, and said force-increasing means includes means for introducing fluid into said fluid cylinder for moving said piston between clamping and unclamping positions relative to an exterior clamping surface. 

1. An electrohydraulic transducer comprising flexible chamber means about which a tubular element is adapted to be exteriorly telescopically positioned, means for introducing a fluid medium into said chamber means, means for supporting a pair of electrodes in said chamber means whereby upon the discharge of electrical energy across said electrodes the resultant electrohydraulic effect produces a momentary hydraulic shock wave which expands said chamber means and forces said tubular element radially outwardly thereby reforming the initial configuration thereof, clamping surface means interiorly contacting a free peripheral edge portion of the tubular element, clamping surface means exteriorly contacting said free peripheral edge portion, means for relatively moving said clamping surface means toward each other to clamp the free peripheral edge portion of the tubular element therebetween thereby clampingly positioning the tubular element at a predetermined position relative to said chamber means, relatively rigid cage structure means disposed partially interiorly of said chamber means, a fluid cylinder carried by said cage structure means, a piston of said fluid cylinder having a surface portion defiNing said interior clamping surface means, and means for introducing fluid into said fluid cylinder for moving said piston between clamping and unclamping positions relative to said exterior clamping surface means.
 2. The electrohydraulic transducer as defined in claim 1 wherein said piston is of an annular configuration and is in exterior telescopic relationship to said chamber means.
 3. The electrohydraulic transducer as defined in claim 2 wherein said chamber means is a flexible baglike element having a closed end, one of said pair of members is supported at said closed end by said supporting means, and one of said electrodes is carried by said one member.
 4. An electrohydraulic transducer comprising flexible chamber means about which a tubular element is adapted to be exteriorly telescopically positioned, means for introducing a fluid medium into said chamber means, means other than said flexible chamber means for clamping the tubular element at a predetermined position relative to said chamber means, and means for increasing the force of said clamping means in proportion to an increase in pressure of said fluid means in said chamber means.
 5. The electrohydraulic transducer as defined in claim 4 including means for supporting a pair of electrodes in said chamber means whereby upon the discharge of electrical energy across said electrodes the resultant electrohydraulic effect produces a momentary shock wave which expands said chamber means and forces said tubular element radially outwardly thereby reforming the initial configuration thereof.
 6. The electrohydraulic transducer as defined in claim 4 wherein said clamping means includes piston means exteriorly of said chamber means, and said force-increasing means is a fluid circuit placing said piston in fluid communication with said chamber means.
 7. The electrohydraulic transducer as defined in claim 4 wherein said clamping means includes a piston axially movable in a fluid cylinder, said piston having a surface portion defining a surface for clamping against a free inner peripheral surface of said tubular element, and said force-increasing means includes means for introducing fluid into said fluid cylinder for moving said piston between clamping and unclamping positions relative to an exterior clamping surface. 